The cheek is tender (5)

I believe the answer is:

brass

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'the cheek' is the definition.
(brass neck can mean cheek or insolence)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for brass that I've seen before include "Family of wind instruments" , "Alloy; money" , "Alloy of Cu and Zn" , "An alloy; part of orchestra" , "Impertinence" .)

I've seen this clue in the Evening Standard.

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